Responding to a VRFY Command

The vrfyallow, vrfydefault, and vrfyhide keywords control the SMTP server’s response when a sending SMTP client issues an SMTP VRFY command.

The vrfyallow keyword tells the MTA to issue a detailed, informative response. The vrfydefault tells the MTA to provide a detailed, informative response, unless the channel option HIDE_VERIFY=1 has been specified. The vrfyhide keyword tells the MTA to issue only a vague, ambiguous response. These keywords allow per-channel control of VRFY responses, as opposed to the HIDE_VERIFY option, which normally applies to all incoming TCP/IP channels handled through the same SMTP server.